text: class Solution:
      def subarraySum(self, nums: List[int], k: int) -> int:
          prefix_sum, prefix_sum_dict = 0, {0 : 1}
          sublist_sum = 0
          for num in nums:
              prefix_sum += num
              if prefix_sum - k in prefix_sum_dict:
                  sublist_sum += prefix_sum_dict[prefix_sum - k]
              if prefix_sum in prefix_sum_dict:
                  prefix_sum_dict[prefix_sum] += 1
              else:
                  prefix_sum_dict[prefix_sum] = 1
          return sublist_sum
  